The stellar death cycle

The death of a star like our sun is but a moment in the long humdrum life of a star. Yet within this moment incredible change occurs that is vital for the development of the universe. In such a star's death throes most of its mass is liberated into the cosmos, briefly forming shells of dust, high-velocity jets, and awe-inspiring nebulae. In a universe that begin with mostly hydrogen and a bit of helium, the mass liberated by a dying star helps enrich the universe with life-essential elements like carbon, oxygen, and nitrogen, which are forged in the star's core. Hence, the life and death of a star becomes a catalyst for life in the universe.

My research probes our understanding of the stellar death cycle, often called the late stages of stellar evolution, touching on phases of heavy mass loss, the Asymptotic Giant Branch (AGB) stars, and their circumstellar environments, to the phase when the mass lost during the AGB is shaped into nebulae with dazzling morphologies, or Planetary Nebulae (PNe). My expertise involves high-energy observations and processes and I utilize satellite observatories that orbit beyond the constraints of our X-ray-opaque atmosphere.

Areas of Focus

I focus on the following phenomenon from the late stages of stellar evolution:

  • extended X-ray emission from hot bubbles confined within planetary nebulae,
  • compact X-ray emission from pre-white dwarf stars and their companions,
  • X-ray and ultraviolet emission from cool AGB stars and their cold detached dust shells.

Additional Projects and Endeavors

Occasionally I dabble in other areas of astrophysics that usually rely partially on an existing experience:

  • Extended X-ray Emission from RS Oph: utilizing my X-ray and imaging experience, with colleagues I have studied the extended emission from the recurrent nova RS Oph.
  • X-ray Calibration with Soft X-ray Sources: I found myself faced with a predicament, all the X-ray photons from this star were in a poorly-calibrated part of the X-ray spectrum, so I worked with Phillip Cargile on statistical modeling of the spectrum to simultaneous estimate the most likely calibration and spectral parameters.